1. Technical Field of the Invention
The present invention relates to a chill roll assembly for drying flexible sheet material and, more particularly, to a chill roll assembly selectively operable to dry one or more continuous sheets.
2. Description of Related Art
Growing demands by consumers for products, such as cellophane or paper, fabricated in sheet form and then cut down to a selected size, has resulted in pressure on manufacturers to increase production for a period of time. However, increasing production is difficult to achieve because such additional production often requires the use of additional equipment. To solve this problem, chill roll machines have been used which allow multiple sheets of material, or webs, to simultaneously pass through the machine for cooling. In one such machine, a first web is passed through an upper set of cooling rolls while a second web is passed through a lower set of cooling rolls. Other than allowing for the processing of multiple webs, or sheets, without requiring an additional machine at additional expense, multi-web machines are advantageously used where the amount of space available for the equipment is limited. On the other hand, a drawback with such machines is that only half of the machine is used if only one web is processed thereby reducing efficiency.
One device used to process webs is a chill roll assembly. A typical chill roll assembly uses one harmonic drive to actuate a set of four chill rolls. The harmonic drive is a device which, when mechanically coupled to a press for driving a plurality of chill rolls, allows the spin speed of the outer surface of the chill rolls to be adjusted a small percentage in relation to the press speed thereby allowing a tension adjustment in the web as it passes through the chill roll apparatus. With the advent of programmable logic controllers, the amount of tension in a given web is programmable and adjustable. Current chill roll assemblies, however, are only adapted to pass one web. Thus, multiple assemblies are required for handling multiple webs.